The Mammalian Gene Collection is intended to provide a publicly available collection of human cDNAs containing the full coding sequence of all known human genes. We are collaborating in providing PCR copies of cDNAs of G protein-coupled receptor (GPCR) genes with particular emphasis on defining the full coding sequence of predicted genes which are not fully supported by reported cDNA sequences. Such predictions are frequently incorrect at one or both ends. Among those that we have fully defined and submitted to Genbank are GPR116, GPR133, GPR139, GPR148, GPR152, GPR158, and GPR158L1.